gh-39473: add tuple typing to gens methods in algebras
    
just adding `-> tuple` to remember that this has been checked.

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
    
URL: #39473
Reported by: Frédéric Chapoton
Reviewer(s): Vincent Macri

Author: Release Manager

src/sage/algebras/askey_wilson.py

@@ -348,7 +348,7 @@ def build_monomial(g):
         return Family(A, build_monomial)
 
     @cached_method
-    def gens(self):
+    def gens(self) -> tuple:
         r"""
         Return the generators of ``self``.
 

src/sage/algebras/clifford_algebra.py

@@ -787,7 +787,7 @@ def gen(self, i):
         """
         return self._from_dict({FrozenBitset((i,)): self.base_ring().one()}, remove_zeros=False)
 
-    def algebra_generators(self):
+    def algebra_generators(self) -> Family:
         """
         Return the algebra generators of ``self``.
 
@@ -801,7 +801,7 @@ def algebra_generators(self):
         d = {x: self.gen(i) for i, x in enumerate(self.variable_names())}
         return Family(self.variable_names(), lambda x: d[x])
 
-    def gens(self):
+    def gens(self) -> tuple:
         r"""
         Return the generators of ``self`` (as an algebra).
 

src/sage/algebras/cluster_algebra.py

@@ -2094,7 +2094,7 @@ def retract(self, x):
         return self(x)
 
     @cached_method
-    def gens(self):
+    def gens(self) -> tuple:
         r"""
         Return the list of initial cluster variables and coefficients of ``self``.
 

src/sage/algebras/down_up_algebra.py

@@ -319,7 +319,7 @@ def algebra_generators(self):
         return Family({'d': d, 'u': u})
 
     @cached_method
-    def gens(self):
+    def gens(self) -> tuple:
         r"""
         Return the generators of ``self``.
 

src/sage/algebras/free_zinbiel_algebra.py

@@ -343,7 +343,7 @@ def change_ring(self, R):
         return FreeZinbielAlgebra(R, n=len(A), names=A, side=self._side)
 
     @cached_method
-    def gens(self):
+    def gens(self) -> tuple:
         """
         Return the generators of ``self``.
 

src/sage/algebras/hecke_algebras/ariki_koike_algebra.py

@@ -532,7 +532,7 @@ def cyclotomic_parameters(self):
             u = cyclotomic_parameters
 
             @cached_method
-            def gens(self):
+            def gens(self) -> tuple:
                 r"""
                 Return the generators of ``self``.
 

src/sage/algebras/hecke_algebras/cubic_hecke_algebra.py

@@ -1415,7 +1415,7 @@ def algebra_generators(self):
         from sage.sets.family import Family
         return Family(self._cubic_braid_group.gens(), self.monomial)
 
-    def gens(self):
+    def gens(self) -> tuple:
         r"""
         Return the generators of ``self``.
 

src/sage/algebras/jordan_algebra.py

@@ -328,7 +328,7 @@ def basis(self):
     algebra_generators = basis
 
     # TODO: Keep this until we can better handle R.<...> shorthand
-    def gens(self):
+    def gens(self) -> tuple:
         """
         Return the generators of ``self``.
 
@@ -763,7 +763,7 @@ def basis(self):
 
     algebra_generators = basis
 
-    def gens(self):
+    def gens(self) -> tuple:
         """
         Return the generators of ``self``.
 
@@ -1316,7 +1316,7 @@ def basis(self):
 
     algebra_generators = basis
 
-    def gens(self):
+    def gens(self) -> tuple:
         """
         Return the generators of ``self``.
 

src/sage/algebras/letterplace/free_algebra_letterplace.pyx

@@ -348,7 +348,7 @@ cdef class FreeAlgebra_letterplace(Parent):
             p *= self._current_ring.gen(j)
         return FreeAlgebraElement_letterplace(self, p)
 
-    def gens(self):
+    def gens(self) -> tuple:
         """
         Return the tuple of generators.
 

src/sage/algebras/lie_algebras/classical_lie_algebra.py

@@ -2170,7 +2170,7 @@ def _part_generators(self, positive=False):
         return Family(I, d.__getitem__)
 
     @cached_method
-    def gens(self):
+    def gens(self) -> tuple:
         r"""
         Return the generators of ``self`` in the order of `e_i`, `f_i`,
         and `h_i`.